The present invention relates to vehicle transmissions and, more specifically, to a manual transmission for vehicles which includes a torsional vibration viscous damper coupling.
Torsional viscous damper couplings to reduce vibration and noise in rotary members are well known in the prior art. Exemplary of such couplings are shown, for example, in U.S. Pat. No. 2,812,648 issued Nov. 12, 1957 to L. P. Croset entitled Couplings for Rotary Members; U.S. Pat. No. 2,738,660 issued Mar. 20, 1956 to S. E. Gail entitled Vibration Damper and U.S. Pat. No. 3,298,240 issued Jan. 17, 1967 to C. H. McDowell et al entitled Floating Pinion For Reduction Gears.
The Croset patent discloses a flexible coupling comprising two coaxial rotary members with one having a plurality of recesses receiving gear teeth-like projections on the other member. The recesses and projections engage achieving a limited freedom of rotary movement about the axis of the members. Spaces are provided forming restricted communication from the forward end of each recess to the rearward end of the recess. Silicone oil of a suitable viscosity fills the recesses and spaces and can be forced through restricted holes and annular recesses forming a fluid reservoir to dampen torsional vibration of power transmission between the members.
The Gail patent discloses a hollow shaft having a flexible quill shaft extending axially therein. The quill shaft is provided with external splines arranged to loosely mate with internal splines in the hollow shaft. Hydraulic fluid is interposed in the cavities between the splines to provide a fluid damper for suppressing vibration in the quill shaft.
The McDowell et al patent discloses inner and outer concentric shafts with reduction gears rigidly mounted on the inner shaft. The outer shaft has a greater inner diameter than the outer diameter of the inner shaft providing an annular space therebetween. An end space is formed between the end of the outer shaft and a coupling structure providing an end space with the inner shaft. Viscous fluid is supplied to one of the spaces to provide a hydrodynamic film between the shafts during their rotation.